Marine Biotoxins: Types and Chemistry

Aspects such as marine biotoxin types and their chemical characteristics; chemistry of domoic acid, okadaic acid and saxitoxin and their analogs; and chemistry of STX and their analogs produced by the phytoplankton and shellfish are dealt with in this chapter. Marine biotoxins are poisons derived from certain kinds of microscopic, toxic algae (marine phytoplankton) in very small amounts. Depending on their chemical structures, these toxins are divided into six groups, viz. , domoic acid (DA), okadaic acid (OA), saxitoxin (STX), brevetoxin (BTX), azaspiracid (AZA), and tetrodotoxin (TTX). All these six groups of bivalve-associated toxins are known to cause four syndromes, viz. , (i) diarrhetic shellfish poisoning, that is, DSP (OA and AZA groups); (ii) amnesic shellfish poisoning, that is, ASP (DA group); (iii) paralytic shellfish poisoning, that is, PSP (STX and TTX groups); and (iv) neurotoxic shellfish poisoning, that is, NSP (BTX group). Other biotoxins such as ciguatoxin, palytoxin, cyclic imines, yessotoxin, pectenotoxin, and so on are found associated with other marine biota ( FAO and WHO, 2016 ). The chemical characteristics of major biotoxins are given in the following table.